During radiation therapy, beams of radiation can pass through a patient. Because radiation beams can kill cancerous tumors as well as healthy tissue and organs, a treatment plan can be formulated to identify the target to be irradiated, the critical structures to be spared, and the intensity of the radiation beams to be used during treatment. Intensity modulated radiation therapy (IMRT) is a form of therapy that irradiates a patient with one or more beams from a plurality of directions and allows precise control over the delivery of radiation. Radioisotopic therapy units can be used in conjunction with IMRT treatment plans.